The present invention relates to security sensors and more particularly to a taut wire sensor for a security post.
A variety of intrusion detection systems are known, ranging from those protecting private residences, to those protecting large-scale, relatively high security facilities such as airports and military installations. A large number of the systems of the second kind, those protecting large-scale facilities, typically provide a combination of a physical barrier and an electron detection capability. A taut wire intrusion detection system provides such a combination. Such systems are available, for example, from Safeguards Technology of Hackensack, N.J. The present invention provides a sensor to be used in such systems.
A typical taut wire intrusion detection system will include sensors, sensor posts, taut wires, anchor posts, and slider posts. A single or several sensors will usually be mounted on a single post, typically referred to as the xe2x80x9cSensor Post.xe2x80x9d Taut wires, commonly double strand steel barbed wire, are attached to the single sensor or to the group of sensors mounted on the Sensor Post. Each taut wire segment (xe2x80x9cTaut Wirexe2x80x9d) usually terminates at two Anchor Posts placed on opposite sides of the Sensor Post to form a subsection of the intrusion detection system. Spiral shaped steel rods are sometimes placed vertically between the Taut Wires as to prevent the wires from bowing or sinking down, these elements are typically referred to as xe2x80x9cSlider Posts.xe2x80x9d Each Taut Wire is maintained in tension between the anchor posts such that the sensor will detect a cut or deflection of the Taut Wire, triggering an alarm at a control center. Multiple subsections constructed in this manner are linked together to secure a given perimeter.
Taut Wire systems are widely used to protect military bases, correctional facilities, airports and many other sites requiring a higher degree of protection than that of a purely physical barrier. Examples of Taut Wire systems employing tension sensors are found in U.S. Pat. Nos. 4,367,459, 4,829,286, and 4,500,873.
In accordance with the invention there is provided a sensor for a taut wire fence, which has a plurality of generally parallel taut wires and a plurality of supporting posts with sensors mounted thereon. The sensor includes a housing, which has an internal cavity with an opening at a first longitudinal end, and which has a land portions around the opening. The housing also has seat portions inside the cavity. The sensor further includes an actuator, which has a taut wire terminal disposed on a first longitudinal end of the actuator, and which has a first electrical terminal and a second electrical terminal. The actuator is adapted to produce an electrical connection between the first electrical terminal and the second electrical terminal in response to skewing of the longitudinal axis of the actuator beyond a threshold angular displacement. The actuator also includes flange portions that extend substantially perpendicular from the outer surface of the actuator substantially near the skewing flexion point of the actuator. The actuator flange portions mate against the housing seat portions. Finally, the sensor includes a first spring element that is disposed between the actuator flange portions and the housing land portions to movably couple the actuator to the housing. In the sensor, the actuator second longitudinal end is within the housing cavity such that the housing cavity limits the movement range of the actuator second longitudinal end to produce a skewing of the actuator when the first longitudinal end is displaced beyond a threshold angle.
In one embodiment, the actuator of the sensor includes a cover, which has a bore having a closed end near a first longitudinal end of the bore and an open end near a second longitudinal end of the bore. The cover has flange portions extending substantially perpendicular from the outer surface of the cover substantially near the second longitudinal end of the bore. The cover also includes a coupling portion extending from the flange portions substantially parallel to the longitudinal axis of the bore, whereby the coupling portion includes inward facing seat portions substantially perpendicular to the longitudinal axis of the bore. The actuator further includes a base, which has a bore having a closed end and an open end, and which has flange portions extending substantially perpendicular from the outer surface of the base substantially near a first longitudinal end of the bore. The base flange portions mate against the cover flange portions. The base further includes an electrical contact disposed inside the bore on a second longitudinal end of the bore. The electrical contact is coupled to a first terminal of the actuator. The actuator also has a contact assembly rigidly coupled to the cover. The contact assembly has a contact wire, which extends out from the cover bore opening substantially along the bore opening longitudinal axis. The contact wire is electrically coupled to a second terminal of the actuator. Finally, the actuator includes a second spring element that is disposed between the base flange portions and the seat portions of the cover coupling portion to movably couple the cover to the base, whereby the contact wire of the contact assembly extends into the actuator base bore spaced apart from at least the electrical contact of the base such that the relative skewing of the cover with relation to the base produces an electrical connection between the electrical contact of the actuator base and the contact wire.